My 03 Ford Taurus develops a thumping vibration in the left front tire after driving at highway speeds. I have the tires rotated and balanced regularly. The tires are original and have only 28000 miles on them. Any suggestions???

Have the tire visually inspected and the wheel checked on a “road force balancing” machine. The machine spins the wheel w/tire while applying a simulated road force via a spinning drum pressed against the wheel. This can detect internal defects that regular machines cannot.

I agree with CapriRacer that this could be a separated belt–which could lead to a sudden blowout. If that was to happen at high speed, the outcome could be very, very bad. With any luck, it is not a separated belt, but this is not something that you should take chances with.

It sounds like your tires are at least 6 years old. Tires are perishable and yours are rotting away.

In accordance with many manufacturers’ (including Ford’s) recommendations, replace your tires after no more than 6 years, regardless of mileage or treadwear. Environmental factors can accelerate tire degradation.

Here’s an independent reference, but also be sure to read your owner’s manual.